Two-photon excited fluorescent silica nanoparticles loaded with iron(II) as a probe for determination and imaging of hydrogen peroxide in living cells

Molybdenum Disulfide Nanocomposites for Cancer Diagnosis and Therapeutics: Biosensors, Bioimaging, and Phototherapy

Molybdenum disulfide (MoS₂) nanomaterials have attracted significant interest in cancer diagnosis and therapy due to their unique physicochemical properties. Due to its extensive surface area and adaptable structure, MoS₂ may engage with pharmaceuticals and biomolecules via covalent and non-covalent interactions. This versatility enhances the sensitivity of identifying specific biomarkers, colloidal stability, and tumor-targeting capabilities. In the near-infrared (NIR) spectrum, MoS₂ exhibits strong optical absorption and efficient photothermal conversion, making it suitable for NIR-driven phototherapy and regulated medication release. Functionalized MoS₂ nanocomposites react differently to the tumor microenvironment, which improves treatment effectiveness by increasing drug accumulation at cancer sites and decreasing off-target effects on healthy tissues. Recent developments in MoS₂-based nanocomposites for cancer detection and treatment are reviewed in this study, with particular attention paid to their uses in photothermal therapy, photodynamic therapy, biosensing, and bioimaging. Additionally, it looks at the difficulties and potential applications of MoS₂ nanocomposites in cancer.

Structure engineering of silicon nanoparticles with dual signals for hydrogen peroxide detection

Fluorescent silicon nanoparticles (SiNPs) were synthesized by a one-step, simple, and green method with 3-Aminopropyltriethoxysilane (APTES) and ascorbic acid (AA) as reaction agents. Subsequently, the SiNPs and AgNPs nanocomplex (SiNPs@AgNPs) was constructed as the probe for hydrogen peroxide (H₂O₂) detection. The fluorescence of SiNPs was quenched due to the surface plasmonic-enhanced energy transfer between SiNPs and AgNPs. Meanwhile, the color tends to be yellow due to the existence of AgNPs. As the AgNPs were etched by H₂O₂, the fluorescence recovers and color fadings. Based on the well-designed structure, the "off-on" fluorescence sensing and "on-off" color sensing platforms for H₂O₂ were fabricated. The as-synthesized materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Fluorescence and UV-vis absorption spectra were used to evaluate the optical performance. The fabricated sensor exhibited a linear range of 1.0-100.0 μM, with a limit of detection of 0.36 μM for the fluorescence sensing of H₂O₂. Additionally, a linear range of 1.0-50.0 μM and a limit of detection of 0.45 μM were displayed for the detection of H₂O₂ by colorimetric assay. The feasibility in complex medium of the fabricated fluorescent and colorimetric dual-signal sensor was evaluated by the detection of H₂O₂ in phosphate buffer saline (PBS) and lake water samples.

A DNAzyme-based label-free fluorescent probe for guanosine-5'-triphosphate detection

Guanosine-5'-triphosphate (GTP) plays a key role in many important biological processes of cells. It is not only a primer for DNA replication and one of the four essential nucleoside triphosphates for mRNA synthesis, but also an energy source for translation and other important cellular processes. It can be converted to adenine nucleoside triphosphate (ATP), and the intracellular GTP level is closely related to the specific pathological state, so it is crucial to establish a simple and accurate method for the detection of GTP. Deoxyribozymes have unique catalytic and structural properties. One of the deoxyribozymes which is named DK2 with self-phosphorylation ability can transfer a phosphate from GTP to the 5' end in the presence of manganese(ii), while lambda exonuclease (λexo) catalyzes the gradual hydrolysis of double-stranded DNA molecules phosphorylated at the 5'-end from 5' to 3', but cannot cleave the 5'-OH end. The fluorescent dye SYBR Green I (SG I) can bind to dsDNA and produce significant fluorescence, but it can only give out weak fluorescence when it is mixed with a single strand. Here, we present a novel unlabeled fluorescence assay for GTP based on the self-phosphorylation of deoxyribozyme DK2 and the specific hydrolysis of λexo. Owing to the advantages of simple operation, high sensitivity, good specificity, low cost and without fluorophore (quenching group) labeling, this method has great potential in biological applications.

A lysosome-targetable two-photon excited near-infrared fluorescent probe for visualizing hypochlorous acid-involved arthritis and its treatment

Lysosome of phagocyte is the main site of hypochlorous acid (HClO) production, and HClO can be employed as the biomarker for the diagnosis and treatment evaluation of arthritis. In recent years, developing fluorescent probes for lysosomal HClO has attracted considerable attention, but most of them still have some defects, such as autofluorescence, phototoxicity and photobleaching because of their excitation and emission located in short-wavelength region. Due to the advantages of two-photon fluorescent probes with near-infrared emissions, a lysosome-targetable two-photon fluorescent probe (Lyso-TP-HClO) with a near-infrared emission was reported in this paper. Lyso-TP-HClO has a high selectivity and a high sensitivity to HClO in the linear range (10.0 × 10^-8 to 5.0 × 10^-6 M), with a detection limit of 3.0 × 10^-8 M. Due to the two-photon excited near-infrared emission, Lyso-TP-HClO has excellent imaging performances, such as small autofluorescence, excellent photostability, and large imaging depth. Furthermore, Lyso-TP-HClO was successfully employed for visualizing lysosomal HClO in bacteria-infected cells. At last, we have successfully used Lyso-TP-HClO to image the arthritis and evaluate the treatment of arthritis in mice. All the results confirm that Lyso-TP-HClO is a useful chemical tool for imaging of lysosomal HClO, the diagnosis of arthritis, and treatment evaluation of arthritis.

Ratiometric fluorescence determination of hydrogen peroxide using carbon dot-embedded Ag@EuWO4(OH) nanocomposites

A sheet-like carbon dot-embedded Ag@EuWO₄(OH) luminescent nanoprobe was successfully developed for assaying hydrogen peroxide. Firstly, the carbon dot-embedded EuWO₄(OH) nanosheets were prepared in a Eu(NO₃)₃·6H₂O-(NH₄)₁₀H₂(W₂O₇)₆·xH₂O-CS(NH₂)₂ hydrothermal synthetic system. Subsequently, the carbon dot-embedded EuWO₄(OH) was functionalized by Ag nanoparticles using an in situ photochemical deposition strategy upon ultraviolet light irradiation. Taking advantage of the dual emissions of the luminescence from carbon dots and characteristic red transitions of Eu³⁺ ions in the integrated system, the carbon dot-embedded Ag@EuWO₄(OH) luminescent composites exhibit ratiometric fluorescence responsive activity towards hydrogen peroxide. The luminescent intensity ratio of Eu³⁺ (614 nm) to carbon dots (389 nm) shows a polynomial function with changing hydrogen peroxide concentration. The corresponding detection limit is 60 μM at a signal-to-noise ratio of 3 (S/N = 3) implying the potential use of the carbon dot-embedded Ag@EuWO₄(OH) as nanoprobe. The method was applied to the quantification of H₂O₂ in real samples with satisfactory results. Graphical abstract A carbon dot-embedded Ag@EuWO₄(OH) luminescence ratiometric probe was successfully prepared through hydrothermal method and in situ photochemical deposition strategy. The luminescence intensity ratio of Eu³⁺ to carbon dots shows synergistic luminescence response activity towards H₂O₂ with detection limit of 60 μM.